A teenager has been spared jail after kidnapping a baby to help her cousin dupe their entire family into thinking she was pregnant.

Sydnee Toulapapa, 19, crept into the sleeping child's bedroom in Auckland and snatched the 11-day-old girl from her cot last August.

Her older cousin, Nadene Manukau-Togiavalu, 21, was the little girl's nanny and had started working for the family just two days earlier, Stuff.co.nz reports.

Sydnee Toulapapa, 19, (pictured) has been spared jail after kidnapping a baby to help her cousin dupe their entire family into thinking she was pregnant

Her older cousin, Nadene Manukau-Togiavalu, 21, spent months wearing a fake fat belt (pictured) and said she was expecting a boy but suspicions grew when the baby shower quickly changed to be for a girl

For months, Manukau-Togiavalu wore a fake fat belly strap under her clothes to convince relatives and her boyfriend she was pregnant and even threw a fake baby shower, the High Court in Auckland heard.

Toulapapa was let off prison and instead escaped with a $2,000 compensation order and 400 hours of community work.